Goodwill and Other Intangible Assets, Summary of Core Deposit and Other Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Summary of core deposit intangibles and other intangibles
Other intangible amortization	$ 2,236	$ 2,814
Core Deposit Intangibles
Summary of core deposit intangibles and other intangibles
Gross carrying amount at the beginning of the year			$ 88,109	$ 80,730
Additions during the period	0		7,379
Accumulated amortization	(23,408)		(21,205)
Net book value	64,701		66,904
Other intangible amortization	2,203		8,749
Other Intangibles
Summary of core deposit intangibles and other intangibles
Gross carrying amount at the beginning of the year			2,000	$ 38,970
Additions during the period	0		200
Accumulated amortization	(683)		(20,385)
Net book value	0		1,350
Other intangible amortization	33		1,443
Other Intangibles | Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member]
Summary of core deposit intangibles and other intangibles
Reductions due to sale	$ (1,317)		$ (17,435)